1. Field of the Invention
This invention relates to a fluid separation device particularly adapted for separating a biological fluid into a liquid and gaseous component without the aid of gravity. More particularly, the device hereof relates to a suction and separation device useful for removing biological fluids during surgical operations in a microgravity environment, such as encountered in outerspace, and for separating the biological liquid component from the entrained air.
2. Description of the Prior Art
Conventional surgical suction and separation units are relatively simple devices designed to extract biological matter, such as blood, away from the area of the surgical operation. Such conventional units typically employ a source of suction, such as a diaphragm-type pump, and a suction tube leading to the surgical cavity. In use, biological matter is removed from the surgical cavity entrained in ambient air. It is advantageous to remove the biological matter from the entraining air medium or damage to the pump may occur. Conventional units include a "drop" chamber connected in series in the suction line between the surgical cavity and the pump. As the biological fluid suspended in the ambient air enters the drop chamber, the liquid and solid components of the biological matter gravitate in the drop chamber with the air and gaseous components being extracted through the pump.
While such drop chamber type suction and separation units are functional in many applications, a number of problems remain. First, such drop chambers are typically several liters in size. If the drop chamber capacity is too small, suction must be discontinued during the surgical process to replace the full drop chamber with an empty one. On the other hand, a drop chamber having several liters of capacity often gives an undesirable slow response time for producing suction during the surgical operation. For example, during the surgical operation, suction is applied intermittently between biological matter, air, and a combination of the two. When the transition is made between conveying air to conveying biological matter, a short response time is present before biological matter is picked up. While such response time is typically of a modest duration, quick response time can be critical in a surgical operation.
Another problem with such conventional drop chamber type suction and separation units is the limitation in capacity of such units. It should be apparent from the above discussion that if the drop chamber has too large of a capacity, the response time for producing suction can become too long to be practical. However, in many cases, drop chamber capacity is insufficient and a pause in operation can result from the necessity to change or empty the drop chamber. Thus, a surgeon faces the choice between a large capacity drop chamber with a long response time and a small capacity drop chamber which must be periodically emptied.
A particular problem addressed by Applicant was the dependence of conventional surgical suction and separation devices upon gravity to achieve the separation of the liquid and solid components of the biological fluid from the gaseous component. With the advent of space-based industrial and research operations, it has become apparent that a broader spectrum of medical problems will affect the space-based personnel. Such space-based operations will necessitate in the future at least some capacity to perform emergency surgery. However, because conventional suction and separation devices are dependent upon gravity, it was necessary to develop alternative methods of removing biological matter during surgery in a microgravity space environment.
One unattractive alternative would be to simply let the biological matter "float" away from the surgical cavity during the operation. Another proposal has been to simply evacuate the biological matter entrained in the cabin air and expel the suspension into outer space. However, a difficulty arises in that the cabin air is unnecessarily evacuated, producing a need to replenish the cabin environment. Still another proposal has been to simply filter the biological matter from the air. However, biological matter quickly clogs filters, rendering this proposal ineffective.
Another approach at solving the problem of providing suction during surgical operations in a microgravity environment is exemplified by U.S. Pat. No. 4,367,728. This disclosure concerns a flexible, transparent envelope which is draped over the patient and includes glove inserts through which the surgeon can perform the operation on the patient. Such an envelope, instead of providing the suction needed during a surgical operation, simply confines the problem to an area surrounding the patient. Of course, the physician's area of operation is limited because of the necessity to use the glove inserts. Also, in more complex operations, the envelope can become sufficiently filled with biological matter to prevent efficient surgery.
Examples of other attempts at handling fluids in a microgravity environment include U.S. Pat. No. 3,828,524 and U.S. Pat. No. 3,988,933.